It is well known to provide a weatherstrip having rows of pile extending longitudinally from a flexible base, and having a substantially impervious barrier comprising a thin film or sheet of plastic material secured to the base and/or to the pile to supplement the sealing action of the pile and increase the resistance to air infiltration through the weatherstrip. An example of this construction is shown in U.S. Pat. No. 3,175,256 in which the barrier member is located between adjacent rows of pile. It is also known to locate the barrier strip on one side of the body of pile as shown in U.S. Pat. No. 3,404,487, or on both sides of the pile as shown in U.S. Pat. No. 3,266,190. U.S. Pat. No. 3,745,053 discloses a weatherstrip having longitudinally extended rows of pile with an impervious barrier strip located between adjacent rows of pile and secured only to the pile.
However, in all of the weatherstrips having pile and a supplemental plastic film or sheet forming a substantially impervious barrier, it has been common practice to form the weatherstrip so that the plastic sheet is substantially the same height as the pile, or slightly below the height of the pile, or in certain instances, slightly above the pile height. However, in all cases, the differential in height between the upper edge of the plastic barrier and the pile has been minimal and these parts have been of substantially the same height. It has been found that despite the advantages of the plastic film in reducing air and moisture infiltration through the weatherstrip, the film increases the break-away force required to open the sliding window or door. Break-away force is defined as the force required to overcome the inertia of the window or door when starting from a fully closed position. The film tends to snap over or reverse itself as the sliding window or door is moved from a fully closed position, thereby increasing the resistance to such movement to the point that the break-away force required to open a door or window has become excessive. Hence, small children or elderly people often cannot open the windows or doors having such weatherstripping.
This invention has for its primary object the provision of a weatherstrip and method for sealing a gap which, although having a thin film or sheet of plastic, or the like, reinforcing the pile bodies to improve the resistance to air moisture infiltration, is so constructed that the opening or break-away force is significantly reduced while maintaining desired sealing properties. It has been found that the break-away force can be reduced by eliminating the plastic barrier member or by shortening it so that it is substantially lower in height than the top of the pile so that when the pile is compressed to the usual degree of approximately 20%, the barrier strip is not substantially bent or flexed. Although such a construction reduces the break-away force, it does not provide satisfactory sealing properties as the resistance of the weatherstrip to water and air infiltration is markedly reduced and an unsatisfactory seal results.